This year the world will spend over $100 billion on vitamins and supplements. Almost one billion of us take one regularly — or give one to our children. Some doctors point to research that shows they can be lifesavers. Many others claim that most vitamin products are useless, and some are downright dangerous. In a world where even the scientists disagree, how do we decide whether to take them, or not? Veritasium's Derek Muller takes us on an epic journey, a world-spanning investigation of vitamin science and history. What he uncovers will confound opinions on all sides.